The invention relates to a drawer guide of the over-extendible type, comprising movement-control means for controlling the movements of the sections of the drawer guide relative to one another in at least the non-over-extended portion of the path of movement of the sections. Such drawer guide is known from U.S. Pat. No. 3,912,341.
The known drawer guide comprises a drawer section, an intermediate section and a case section. The case section has a substantially U-shaped crsoss-section, having a short first leg and a relatively long second leg, with which the case section cann be attached to a case wall. The intermediate section has a generally E-shaped cross-section and overlaps the first leg of the case section, a slide-bearing element being positioned there between. The drawer section has a substantially U-shaped cross-section overlapping the top side of the intermediate section. A wheel shaped bearing is positioned between the middle bar of the E-shaped intermediate section, the axis of rotation of the wheel being attached to the case section. Thus the intermediate section is positioned substantially above the case section, the drawer section being positioned substantially above the intermediate section, partly enclosed between the case section and the intermediate section. This known drawer guide is thus relatively bulky.
On the wall of the intermediate section, extending vertically, a first and second guide wheel are provided, one near each end of said section, having an axis of rotation extending horizontally, perpendicular to said wall. A wire shaped connecting element is guided around said wheels. A first coupling is connected to the wire and the case section in a first position, a second coupling to the wire and the drawer section in a second position, the first and second positions being apart over half the length of the wire. Thus, when the drawer section is moved relative to the intermediate section, the case section is moved over the same distance and in opposite direction relative to the intermediate section. The drawer guide is of the over extendible type.
This known drawer guide has the disadvantage that the connecting element extends in a vertical plane, parallel to the wall of the intermediate section. This means that a relatively large space has to be available between the intermediate section and the drawer section to provide for the wheels, the wire shaped element and the couplings. Furthermore, the wire shaped element can run on the wheels, impairing a proper functioning of the drawer guide.
U.S. Pat. No. 3,912,341 discloses a drawer guide comprises a case section and a drawer section disposed parallel thereto, while between the case section and the drawer section, an intermediate section is included. The drawer section and the case section are bearing-mounted so as to be movable relative to the intermediate section. The sections are constructed so that the sections are movable into an end position wherein the drawer section and the case section no longer overlap, the so-called over-extended end position. In the intermediate section, a window is provided accommodating a roller manufactured from resilient material. As long as the case section and the drawer section both overlap the window, the roller abuts on one side of the window against the inside of the case section and on the opposite side against the inside of the drawer section. This involves the roller being slightly compressed so that there is a firm frictional contact. The roller acts as movement-control means for the sections, so long as the case section and the drawer section both overlap the window. This can be understood as follows.
During use, the roller can only rotate within the window about an axis in the plane of the window, at right angles to the direction of movement of the sections. When the intermediate section moves relative to the case section in a first direction, the roller is rotated as a result of the friction, while pushing away the drawer section and vice versa. The distance travelled by the drawer section relative to the intermediate section is equal to the movement of the intermediate section relative to the case section. This has as a result that during the part of the path of movement in which the roller contacts both the drawer section and the case section, the movement of such a guide and, accordingly, for instance a drawer suspended therefrom, is even, quiet and accurately controlled.
However, the known drawer guide has the drawback that in the portion of the path of movement where the case section and the drawer section no longer both overlap the window, the movements of the drawer section relative to the case section are no longer controlled, while, moreover, at least either the case section or the drawer section can move freely relative to the intermediate section. This creates a relatively abrupt transition in the path of movement and in the movement pattern of the drawer guide when one of the sections loses contact with the roller, or, by contrast, enters into contact therewith, the more so because this involves the roller suddenly springing outward or having to be slightly compressed. This relatively abrupt transition has as a consequence that the movement pattern of a drawer suspended by such drawer guides is uneven and hence unpleasant, while, moreover, the contents of such drawer may easily start to move through the drawer due to an occurring impact. Further, because of this transition, an irksome noise is created. A further drawback is that due to the roller continuously entering into and losing contact with at least one of the sections, the roller will be subject to wear, while, moreover, this wear could be irregular because the position of the roller at the moment of entering into contact will always be substantially the same. As a consequence, the roller will in the end become asymmetrical and hence produce a jerky movement pattern.
A further major drawback of this known drawer guide is that the roller is subject to wear, because through a portion of the path of movement it slides over one of the sections rather than rolling therealong. This causes a flattening of at least a part of the tread of the roller, which adversely affects the rolling properties thereof. This can be understood as follows. When the guide is being slid in, the first section will already reach the end position relative to the intermediate section, while this does not yet apply to the third section. Hence, in the final part of the sliding-in path of the third section, rotation of the roller is prevented by the first section, and therefore, the roller starts to slide over the first section and wear occurs.
German Offenlegungsschrift 2 307 041 discloses a comparable drawer guide, with the case section extending along the bottom side of the intermediate section and the drawer section extending along the top side thereof. Between the top side of the case section and the bottom side of the drawer section, a runner is included as control means. This known drawer guide has drawbacks comparable with the drawbacks of the above-described drawer guide.
Dutch Patent Application NL-A-8304456 discloses a drawer guide of the overextendible type, in which the ball cages between first and second and second and third section respectfully are interconnected by two cables, such that upon movement of one of the ball cages the second ball cage moves over the same distance in opposite direction. The outer sections then move in opposite directions relative to the intermediate section due to friction of the ball cages to the respective sections. This drawer guide has the disadvantage that these sections can move relative to the respective ball cages independently from the other sections, by sliding over the ball cages, overcoming said friction.